Late by 1day

I was suppose to start today and didn't. Normally I am dead on with this app and actually start having the brown yuck stuff a few days before period starts. I took a .88 test today that was clearly negative. Could it just be to early to test or aunt flow probably gonna show her face? 
Symptoms: 
Gassy
Nausea
Increase appetite 
Trouble pooping. 
Trouble sleeping
Headaches 
Metallic taste when drinking water